System for Crowd-Sourced Fingerprinting

ABSTRACT

A system for crowd-sourced fingerprinting has a positioning database and a mobile wireless device. The positioning database is configured to store information relating wireless local area network access point (AP) signal measurements to points of a geographic positioning grid. The mobile wireless device has a satellite positioning system, a transceiver, a motion measurement system, and position estimation logic. The position estimation logic is configured to determine a reference location as the device passes between areas of satellite positioning signal reception and satellite positioning signal non-reception. The device further configured to record measurements of movements provided by the motion measurement system and measurements of signals provided by the transceiver within areas of non-reception and to provide results to the positioning database.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of and claims priority to U.S. patentapplication Ser. No. 13/462,386 filed on May 2, 2012. Said applicationincorporated by reference in its entirety for all purposes.

BACKGROUND

As mobile devices proliferate, the demand for services tailored todevice location also increases. Location based services depend onpositioning systems to determine device location. Satellite basedpositioning systems, such as the global positioning system (GPS),GLONASS, and Galileo can provide high accuracy, but require a clear lineof sight between the satellites and the mobile device to provide aposition determination. Consequently, satellite positioning systems arelargely ineffective for indoor positioning. Satellite positioning alsorequires specialized receivers that may increase the cost of the mobiledevice.

As an alternative or an augmentation to satellite based positioning,wireless local area network (WLAN) based positioning systems have beendeveloped. WLAN based positioning systems are suitable for indoorpositioning and require minimal investment because they make use ofexisting infrastructure. Furthermore, many mobile wireless devicesinclude support for communication via WLAN. Systems that provideimprovements in indoor positioning are desirable.

SUMMARY

A system and method for indoor positioning based on wireless local areanetwork fingerprinting are disclosed herein. In one embodiment a methodfor indoor positioning includes determining, by a wireless device, areference location of the wireless device, based on satellitepositioning, as the device passes between areas of satellite positioningsignal reception and satellite positioning signal non-reception. Whilein the areas of non-reception, the wireless device measures signalstransmitted by wireless local area network (WLAN) access points (APs).While in the areas of non-reception, the wireless device measuresparameters of motion of the wireless device. Positions of the wirelessdevice in the areas of non-reception are estimated based on thereference location and the parameters of motion. A positioning grid forpositioning is generated based on the signals measured by the wirelessdevice at the estimated positions.

In another embodiment, a wireless device includes a satellitepositioning system, a WLAN transceiver, a motion measurement system, anda position estimation system. The satellite positioning system isconfigured to determine a location of the wireless device based onreceived satellite positioning signals. The WLAN transceiver isconfigured to measure while in the areas of non-reception, signalstransmitted by WLAN APs. The motion measurement system is configured tomeasure movement of the wireless device. The position estimation systemis configured to determine a reference location of the wireless device,based on satellite positioning, as the device passes between areas ofsatellite positioning signal reception and satellite positioning signalnon-reception. The position estimation system is also configured torecord measurements of movement of the wireless device and measurementsof WLAN AP signals within areas of satellite positioning signalnon-reception. The position estimation system is further configured toprovide the reference location and the recorded measurements to apositioning database that generates a positioning grid for positioningbased on the WLAN AP signals measured by the wireless device at thepositions estimated from the measurements of movement.

In a further embodiment, a system for crowd-sourced fingerprintingincludes a positioning database and a mobile wireless device. Thepositioning database is configured to store information relating WLAN APsignal measurements to points of a geographic positioning grid. Themobile wireless device includes a satellite positioning system, a WLANtransceiver, a motion measurement system, and position estimation logic.The position estimation logic is configured to determine a referencelocation of a wireless device, based on satellite positioninginformation provided by the satellite positioning system, as the devicepasses between areas of satellite positioning signal reception andsatellite positioning signal non-reception. The position estimationlogic is also configured to record measurements of movement of thewireless device provided by the motion measurement system andmeasurements of WLAN AP signals provided by the WLAN transceiver withinareas of non-reception. The position estimation logic is furtherconfigured to provide the reference location and the recordedmeasurements to the positioning database.

In yet another embodiment, a positioning server includes a positioningdatabase. The positioning database is configured to store informationrelating wireless local area network (WLAN) access point (AP) signalmeasurements to points of a geographic positioning grid; to store motioninformation provided by dead-reckoning systems of a plurality ofwireless devices and reference location information provided by at leastone of a satellite positioning system and a wireless local area network(WLAN) positioning system of each wireless device; and to store WLANaccess point (AP) signal measurements acquired by each wireless devicein correspondence with the motion information. The positioning databaseis also configured to non-causally determine positions of the wirelessdevices based on the motion information and reference locations; and togenerate a geographic positioning grid that relates the AP signalmeasurements to points of the positioning grid based on the determinedpositions.

BRIEF DESCRIPTION OF THE DRAWINGS

For a detailed description of exemplary embodiments of the invention,reference will now be made to the accompanying drawings in which:

FIG. 1 shows a block diagram for a system for indoor positioning thatincludes crowd-sourced fingerprinting in accordance with variousembodiments;

FIG. 2 shows a block diagram for a wireless device configured for indoorpositioning using crowd-sourced fingerprinting in accordance withvarious embodiments; and

FIG. 3 shows a flow diagram for a method for indoor positioning usingcrowd-sourced fingerprinting in accordance with various embodiments.

NOTATION AND NOMENCLATURE

Certain terms are used throughout the following description and claimsto refer to particular system components. As one skilled in the art willappreciate, companies may refer to a component by different names. Thisdocument does not intend to distinguish between components that differin name but not function. In the following discussion and in the claims,the terms “including” and “comprising” are used in an open-endedfashion, and thus should be interpreted to mean “including, but notlimited to . . . .” Also, the term “couple” or “couples” is intended tomean either an indirect or direct electrical connection. Thus, if afirst device couples to a second device, that connection may be througha direct electrical connection, or through an indirect electricalconnection via other devices and connections. Further, the term“software” includes any executable code capable of running on aprocessor, regardless of the media used to store the software. Thus,code stored in memory (e.g., non-volatile memory), and sometimesreferred to as “embedded firmware,” is included within the definition ofsoftware. The recitation “based on” is intended to mean “based at leastin part on.” Therefore, if X is based on Y, X may be based on Y and anynumber of other factors.

DETAILED DESCRIPTION

The following discussion is directed to various embodiments of theinvention. Although one or more of these embodiments may be preferred,the embodiments disclosed should not be interpreted, or otherwise used,to limit the scope of the disclosure, including the claims. In addition,one skilled in the art will understand that the following descriptionhas broad application, and the discussion of any embodiment is meantonly to be exemplary of that embodiment, and not intended to intimatethat the scope of the disclosure, including the claims, is limited tothat embodiment.

One solution for indoor positioning involves wireless local area network(WLAN) fingerprinting. See, e.g., Teemu Roos et al., A ProbabilisticApproach to WLAN User Location Estimation, INT'L J. OF WIRELESS INFO.NETWORKS, July 2002, at 155. In WLAN fingerprinting, a database includeslocation information associated with received signal strengthmeasurement values from WLAN access points (APs) that were generatedduring a database creation phase. In one variant of WLAN fingerprinting,received signal strength measurement values at a given location areestimated based on a radio frequency (RF) propagation model, thusrequiring no actual measurement of signal strengths. A higher-complexityvariant of WLAN fingerprinting takes actual measurements of signalstrength at all possible locations (e.g., all points of a positioninggrid) within an area to be mapped. The performance of fingerprintingsystems based on RF propagation models may be suboptimal, while the costof the higher-complexity system may be prohibitive.

Embodiments of the present disclosure build a fingerprinting databasefrom information actively or passively provided by a plurality ofwireless devices as the wireless devices traverse the indoor space beingmapped (i.e., fingerprinted). Each wireless device contributing to thefingerprint database provides dead-reckoning information and receivedsignal strength information to the database. The database uses theinformation to map signal strength for each access point to geographiclocations.

FIG. 1 shows a block diagram for a system for indoor positioning thatincludes crowd-sourced fingerprinting in accordance with variousembodiments. The system 100 includes a plurality of APs 104, a wirelessdevice 102, and a positioning database 114. Each of the APs 104 isconfigured to communicate with the wireless device 102 via a WLAN, e.g.,a WLAN in accordance with an IEEE 802.11 standard. The APs 104 aredisposed such the wireless device 102 can receive signals transmitted bythe APs 104 as the wireless device 102 traverses the interior of thestructure 106.

The wireless device 102 is configured to wirelessly communicate with oneor more of the APs 104. In the embodiment of FIG. 1, the wireless device102 is positioned to receive transmissions from and/or communicate withany of the APs 104. The wireless device 102 includes a satellitepositioning system and a dead-reckoning system. The wireless device 102may be a cellular telephone, a tablet computer, or any other mobilecomputing device configured for WLAN access, satellite positioning, andmotion measurement. While only four APs and single mobile wirelessdevice are shown in FIG. 1, in practice the system 100 may include anynumber of wireless devices 102 and APs 104.

The structure 106 may be a building or other area within which satellitepositioning is unavailable or undesirable. The structure 106 includespathways 112 over which the wireless device 102 may traverse theinterior of the structure 106. In FIG. 1, the wireless device 102 entersthe structure 106 at entry point 108, and traverses the interior of thestructure 106 on pathways 112 to exit point 116. The regions 110represent areas within the structure 106 that are not pathways 112traversable by the wireless device 102.

While able to receive satellite signals (e.g., outside the structure106), the wireless device 102 determines its location via satellitepositioning. After entering the structure 106, satellite positioning maybe unavailable or inaccurate. Therefore, the wireless device 102 appliesdead-reckoning within the structure 106, based on a last determinedsatellite position, and provides motion and AP signal strengthinformation to the positioning database 114 as the wireless device 102traverses the interior of the structure 106.

The positioning database 114 stores motion and AP signal strengthinformation provided by the wireless device 102 and a plurality of otherwireless devices. Dead-reckoning may be accurate for a limited timeafter the wireless device 102 enters the structure 106. Consequently,the positioning database 114 may be initially populated only with regardto the area of the structure 106 near the entry point 108. Over time thepositioning database 114 refines dead-reckoning positions and the APsignal strengths observed by devices at various points on the pathways112, and provides the location and signal strength information towireless devices traveling further into the structure 106 allowing allthe pathways 112 to be mapped. As the fingerprinting informationprovided by the database 114 becomes more accurate, the wireless device102 can determine its location in the structure via WLAN positioning andprovide dead-reckoning positions and AP signal strengths from locationsfarther into the interior of the structure 106. In this manner, theentirety of the pathways 112 is eventually mapped. Thus, the positioningdatabase 114 and the wireless device 102 cooperate to generate acrowd-sourced WLAN fingerprinting system for use in indoor positioning.

FIG. 2 shows a block diagram of the wireless device 102. The wirelessdevice 102 is configured for indoor positioning using crowd-sourcedfingerprinting in accordance with various embodiments. The wirelessdevice 102 includes a WLAN transceiver 202, a satellite positioningsystem 210, and motion sensors 212 each of which provide information tothe position estimation and cooperative fingerprinting module 208(position estimation module 208). The WLAN transceiver 202 provides aninterface through which the wireless device 102 accesses the wirelessmedium to communicate with one or more of the APs 104. The WLANtransceiver 202 receives signals transmitted by the APs 104 and derivessignal strength values, such as received signal strength indicator(RSSI) values, from the received signals.

The satellite positioning system 210 is configured to receivepositioning signals transmitted by positioning satellites, and based onthe time of flight of positioning signals received from a plurality ofpositioning satellites, determine the position of the wireless device102. The satellite positioning system 210 can resolve the position ofthe wireless device 102 when provided with an unobstructed view of atleast four of the positioning satellites. The satellite positioningsystem 102 may be a GPS receiver or any other system configured todetermine the position of the wireless device 102 based on signalsreceived from a satellite.

The motion sensors 212 measure parameters of displacement, movement,and/or location of the wireless device. The motion sensors 212 mayinclude accelerometers, gyroscopes, magnetometers, barometers, etc. Atleast some such sensors may be implemented as MEMS(microelectromechanical systems) devices. Information provided by thesensors 212 may be used to extrapolate the location of the wirelessdevice 102 based on a last known position obtained via satellite or WLANpositioning when the wireless device 102 is traversing the interior ofthe structure 106.

The position estimation module 208 collects the positioning informationgenerated by the satellite positioning system 210, the motion sensors212, and the WLAN transceiver 202 and, based on the collectedinformation, may estimate the position of the wireless device 102. Thus,the position estimation module 210 may include a WLAN positioning systemthat determines the position of the wireless device 102 based onstrength of received AP signals and fingerprint information provided bythe database 114.

The position estimation module 208 also provides the collectedpositioning information (signal strengths, motion information, etc.) tothe positioning database 114. In some embodiments of the wireless device102, the positioning database 114 may be disposed within the wirelessdevice 102. In some embodiments, the positioning database 114 mayexternal to the wireless device 102 (e.g., on a server) and accessibleto the wireless device 102 via one of the APs 104 or via a differentcommunication network (e.g., a wireless wide area network).

To provide additional positioning information while traversing theinterior of the structure 106, some embodiments of the wireless device102 include one or more additional RF receiver 204, a magnetometer 206,and/or a map 214. The additional RF receivers 204 may be a wirelesstelephone receiver, a broadcast frequency modulated (FM) signalreceiver, a personal area network (e.g., BLUETOOTH) receiver, a digitaltelevision (DTV) signal receiver, etc. The RF receiver 204 measures aparameter of the received RF signal (e.g., signal power) and providesthe parameter measurements to the position estimation module 208.

The magnetometer 206 may provide a heading or travel direction, e.g., adirection relative to magnetic north, to the position estimation module208. The magnetometer 206 may also provide measurements of magneticfield strength proximate to the wireless device 102 to the positionestimation module 208. The measurements of magnetic field strength maybe used by the database 114 to build a map of magnetic fields within thestructure 106, and to position the wireless device 102 based on measuredstrength of the magnetic fields in conjunction with measured AP/RFsignal strength. Functions of the magnetic field strength data, such asthe norm of the magnetic field, may also be used to construct afingerprint of the magnetic fields of the structure 106.

The map 214 provides information defining the pathways 112 of thestructure 106. Some embodiments of the position estimation module 208apply the map data to improve a position determined based on the motionsensors 212. For example, if dead-reckoning places the wireless device102 in a region 110 of the structure 106 (i.e., not on a pathway 112) asdefined in the map 214, then the position estimation module 208 may deemthe position of the wireless device 102 to be the nearest positionwithin a pathway 112. In some embodiments, the map 214 is storedexternal to the wireless device 102. The positioning database 114 mayuse the map 214 non-causally to resolve the location of the wirelessdevice 102. For example, the positioning database 114 may apply the map214 to refine past locations of the wireless device 102. Given anaccurate map, map matching can be extremely effective. In manybuildings, there are a limited number of possible routes. Even withrelatively inaccurate dead-reckoning, the correct route can be estimatedusing measurements from the entire route. Embodiments may apply any ofvarious map matching algorithms known in the art. For example, someembodiments may implement map matching using a Viterbi algorithm. See,e.g., Arvind Thiagarajan et al., VTrack: Accurate, Energy-aware RoadTraffic Delay Estimation Using Mobile Phones (2009).

The position estimation module 208 collects the various signalmeasurements (AP received signal strength, RF power, magnetic field,etc.) along with measurement time information, such as time-stamps, andsignal source information, such as AP media access controller addresses,sometimes referred to as BSSID (Basic Service Set Identifier). Thecollected information may be provided to the database 114 at or near thetime of collection, or stored for provision to the database 114 at alater time, for example, at a preset interval or when a predeterminedquantity of data is collected or when the device has free access to theinternet (not roaming).. Similarly, the position estimation module 208collects motion information (e.g., speed, acceleration, heading, etc.)from the motion sensors 212 and provides the information along with timeof acquisition to the database 114. The sampling of motion informationmay be uniform (e.g., once per second), or non-uniform (e.g., per userstep).

The motion sensors 212 and the position estimation module 208 maycomprise an inertial navigation system or may apply pedestriandead-reckoning techniques as appropriate (e.g., vehicular versuspedestrian applications). Speed and heading may be provided to thedatabase 114 as velocities in east, north, and up coordinates, andhorizontal and vertical speeds and/or displacements may be separatelyprovided.

In some embodiments, the position estimation module 208 may estimate theposition of the wireless device 102 based on the motion information andprovide the estimated position to the database 114. In otherembodiments, the database 114 performs the position estimation. Thus,the wireless device 102 can operate as measuring device and providemeasurements to the positioning database 114. Different embodiments ofthe position estimation module 208 may provide different levels ofprocessing. For example embodiments may trade-off the amount of datauploaded and the amount of computations/memory required at the wirelessdevice 102.

In some embodiments of the wireless device 102, the position estimationmodule 208 sets a heading for dead-reckoning based on satellitepositioning prior to entry of the structure 106. Given an initialheading based on satellite positioning, the position estimation module208 may compute the motion parameters (device displacement) withoutcomputing an absolute heading. Such heading initialization isadvantageous because the magnetometer 206 is not required, although themagnetometer 206 may also be used to establish a heading in someembodiments. The initial heading computed based on satellite positioningmay be the bearing angle between two different position estimates (whichare computed using pseudorange measurements), or the satellite signalsalso allow heading to be computed directly through Doppler frequencymeasurements. In practice, both pseudorange and Doppler frequencymeasurements may be used to compute this initial heading.

In embodiments that establish an initial heading based on satellitepositioning, dead-reckoning can be performed based on an accelerometerand a gyroscope, where the gyroscope provides heading changeinformation. Gyroscope data may be provided with or without bias removalalong with bias, where bias removal reduces the number of bitstransferred or the number of server computations. The satellitedetermined heading can be used to calibrate the magnetometer 206. Themagnetometer 206 also provides heading information in environments thatare relatively free of magnetic noise. For information regardingcalibration of the magnetometer 206 based on the satellite determinedheading, see U.S. Provisional Patent Application 61/522,112, filed Aug.10, 2011, which is hereby incorporated herein by reference in itsentirety.

The position estimation module 208 can determine the location of thewireless device 102 based on satellite position when the wireless device102 exits the structure 106 at point 116. Based on the current satellitedetermined location, the position estimation module 208 can estimate,from stored motion information, the position of the wireless device 102at different points as it approached the exit point 116. Such estimationis non-causal because current measurements are used to determineprevious locations.

Thus, the position estimation module 208 can estimate the position ofthe wireless device 102 within the structure 106 at a given time basedon satellite positions determined at both entry point 108 and exit point116, effectively doubling the number of measurements provided to thepositioning database 114. The heading of the wireless device 102 on exitmay also be determined based on satellite positioning, and used toimprove estimates of the position of the wireless device 102 as itapproached the exit point 116. As previously explained, the database 114may be configured to determine the location of the wireless device 114based on satellite position, motion information, etc. provided by theposition estimation module.

Various components of the mobile wireless device 102 and the positioningdatabase 114 including at least some portions of the position estimationmodule 208 can be implemented using a processor executing softwareprogramming that causes the processor to perform the operationsdescribed herein. In some embodiments, a processor executing softwareinstructions causes the wireless device 102 to collect motioninformation and signal strength information, and provide the informationto the positioning database. Further, a processor executing softwareinstructions can aggregate motion and signal strength information from aplurality of wireless devices and generate, based on the information, afingerprint for the interior pathways 112 of the structure 106.

Suitable processors include, for example, general-purposemicroprocessors, digital signal processors, and microcontrollers.Processor architectures generally include execution units (e.g., fixedpoint, floating point, integer, etc.), storage (e.g., registers, memory,etc.), instruction decoding, peripherals (e.g., interrupt controllers,timers, direct memory access controllers, etc.), input/output systems(e.g., serial ports, parallel ports, etc.) and various other componentsand sub-systems. Software programming (i.e., processor executableinstructions) that causes a processor to perform the operationsdisclosed herein can be stored in a computer readable storage medium. Acomputer readable storage medium comprises volatile storage such asrandom access memory, non-volatile storage (e.g., a hard drive, anoptical storage device (e.g., CD or DVD), FLASH storage,read-only-memory), or combinations thereof. Processors execute softwareinstructions. Software instructions alone are incapable of performing afunction. Therefore, in the present disclosure any reference to afunction performed by software instructions, or to software instructionsperforming a function is simply a shorthand means for stating that thefunction is performed by a processor executing the instructions.

In some embodiments, portions of the mobile wireless device 102,including portions of the position estimation module 208 may beimplemented using dedicated circuitry (e.g., dedicated circuitryimplemented in an integrated circuit). Some embodiments may use acombination of dedicated circuitry and a processor executing suitablesoftware. For example, some portions of the position estimation module208 may be implemented using a processor or hardware circuitry.Selection of a hardware or processor/software implementation ofembodiments is a design choice based on a variety of factors, such ascost, time to implement, and the ability to incorporate changed oradditional functionality in the future.

FIG. 3 shows a flow diagram for a method 300 for indoor positioningusing crowd-sourced fingerprinting in accordance with variousembodiments. Though depicted sequentially as a matter of convenience, atleast some of the actions shown can be performed in a different orderand/or performed in parallel. Additionally, some embodiments may performonly some of the actions shown. In some embodiments, at least some ofthe operations of the method 300, as well as other operations describedherein, can be performed by a processor executing instructions stored ina computer readable medium.

In block 302 the wireless device 102 is passing from an area ofsatellite signal reception to an area of satellite signal non-reception.For example, the wireless device 102 is entering the structure 106.While receiving satellite positioning signals, the wireless device 102determines its position and heading via satellite positioning. Thewireless device 102 initializes a dead-reckoning system of the wirelessdevice 102 based on the satellite derived position and heading. Thedead-reckoning system provides motion and/or position information to thewireless device 102 while operating in the area of satellite signalnon-reception (e.g., within the structure 106).

In block 304, the wireless device 102 measures signals transmitted bythe APs 104. The wireless device 102 may measure the received signalstrength (e.g., RSSI) of signals transmitted by the APs 104. Thewireless device 102 may also measure a parameter (e.g., received signalpower) of other RF signals. For example, the wireless device 102 maymeasure personal area network (e.g., BLUETOOTH) signals, FM broadcastsignals, DTV broadcast signals, mobile telephone signals, etc. Thewireless device 102 may store the measured signal parameters along witha value indicating time of measurement (e.g., a time stamp) and providethe measured parameters and associated time stamps to the database 114for use in constructing a fingerprint of the structure 106.

In block 306, the wireless device 102 measures magnetic field strengthin the vicinity of the wireless device 102. Like the RF signalmeasurements, the magnetic field strength measurements are time-stampedand provided to the database 114 for use in constructing a fingerprintof the structure 106.

In block 308, the wireless device 102 measures one or mores parametersof motion or location that can be used to position the device in lieu ofsatellite positioning. For example, the wireless device 102 may measureheading, speed, acceleration, altitude, etc. In some embodiments, themotion/location measurements are time-stamped and provided to thedatabase 114 for use in constructing a fingerprint of the structure 106.

In block 310, the wireless device 102 or the database 114 processes themotion/location measurements to estimate device location within thestructure 106 at the time of measurement acquisition. Thus, in someembodiments, the wireless device 102 provides position estimates to thedatabase 114. A position estimate may be with reference to satelliteposition determined at entry point 108 or exit point 116, or withreference to WLAN positioning based on AP signal strengths and the WLANfingerprint of the structure 106 developed over time by the database114. Thus, for at least some motion/location information acquired by thewireless device 102, two position estimates may be derived—a firstestimate referenced to entry point 108 and a second estimate referenceto exit point 116. In some embodiments, position estimates maydetermined based on a map of the internal pathways 112 of the structure106.

In block 312, the database 114 aggregates the signal strengthinformation and motion/location information provided by the wirelessdevice 102 with signal strength information and motion/locationinformation provided by other wireless devices traversing the pathways112 of the structure 106. Based on this information, the database 114constructs a fingerprint of the structure 106 that relates positionwithin the structure 106 to parameters (e.g., signal strength) ofsignals (e.g., AP transmissions) observed by devices at the position.The fingerprint may be in the form of grid. The database 114 developsthe fingerprint over time as additional data from wireless devices isacquired. In some embodiments, construction of the fingerprint begins atthe entry and exit points 116 (based on satellite positioning) andextends inward through the structure 106 as WLAN and/or other RF ormagnetic field position becomes accurate enough to extend the reach ofdead-reckoning.

The above discussion is meant to be illustrative of the principles andvarious embodiments of the present invention. Numerous variations andmodifications will become apparent to those skilled in the art once theabove disclosure is fully appreciated. It is intended that the followingclaims be interpreted to embrace all such variations and modifications.

What is claimed is:
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 17. A system forcrowd-sourced fingerprinting, comprising: a positioning databaseconfigured to store information relating wireless local area network(WLAN) access point (AP) signal measurements to points of a geographicpositioning grid; and a mobile wireless device comprising: a satellitepositioning system; a WLAN transceiver; a motion measurement system; andposition estimation logic configured to: determine a reference locationof a wireless device, based on satellite positioning informationprovided by the satellite positioning system, as the device passesbetween areas of satellite positioning signal reception and satellitepositioning signal non-reception; record measurements of movement of thewireless device provided by the motion measurement system andmeasurements of WLAN AP signals provided by the WLAN transceiver withinareas of non-reception; provide the reference location and the recordedmeasurements to the positioning database.
 18. The system of claim 17,further comprising a positioning server that comprises the positioningdatabase.
 19. The system of claim 17, wherein at least one of theposition estimation logic and the database is configured to estimatepositions of the wireless device in the areas of non-reception based onthe reference location and the measurements of movement, and provide theestimated positions to the database for use in generating thepositioning grid.
 20. The system of claim 17, wherein the databasecomprises a map of the areas of non-reception and at least one of theposition estimation logic and the database is configured to apply themap to estimate positions of the wireless device in the areas ofnon-reception.
 21. The system of claim 17, wherein the motionmeasurement system comprises at least one of an accelerometer, agyroscope, a magnetometer, and a barometer that measure movement of thewireless device.
 22. The system of claim 17, wherein at least one of theposition estimation logic and the database is configured to estimatepositions of the wireless device in the areas of non-reception based onboth a previously reference location determined prior to measurement ofmovement and a reference location determined subsequent to measurementof movement; wherein each reference location is based on one ofsatellite positioning and WLAN positioning.
 23. The system of claim 17,wherein the position estimation logic is configured to determine, basedon satellite positioning, the reference location as the wireless deviceenters or exits the areas of signal non-reception.
 24. The system ofclaim 17, wherein the position estimation logic is configured to:determine a heading, based on satellite positioning, as the wirelessdevice enters or exits areas of non-reception; and initialize the motionmeasurement system based on the determined heading.
 25. The system ofclaim 17, wherein the wireless device comprises at least one receiverselected from: a personal area network receiver, frequency modulationbroadcast band receiver, wireless telephone receiver, and a digitaltelevision broadcast band receiver, each receiver configured to measuresignals corresponding to the receiver while in the areas ofnon-reception; and wherein the position estimation logic is configuredto: record measurements of the signals within the areas ofnon-reception; and provide the recorded measurements to the database;and wherein the database is configured to generate the positioning gridfor positioning based on the measurements of the signals correspondingto the receivers.
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